COUNTRY FILES (Contd.)

RWANDA (Contd.)

LAKE MUGESERA

LAKE MUHARI

LAKE MUHAZI (= MOHASI)

LAKE MURAGO (= RUMIRA)

LAKE NASHO

LAKE NGERENKE

LAKE RUGWERO
(International water)

LAKE RUKIRA

LAKE RWAMPANGA (= MPONGA)

LAKE RWANYAKIZINGA (= RWANYE)

LAKE RWEHIKAMA

LAKE SAKE

AKAGERA SWAMPS
(International water)

RUGEZI (= RUGUESI) SWAMP

AKAGERA RIVER
(International water)

Fisheries data
Potential annual yield: 200 t in Rwanda (Aubray, 1976)

RUZIZI RIVER
(International water)

7. BIBLIOGRAPHY
(except Lake Kivu: see ZAIRE)

Aubray, 1976
Burgis, Mavuti, Moreau and Moreau, 1987
Corsi et al., 1986
Damas, 1954
Dunn, 1974
Frank, 1987
Frank et al., 1984
Giudicelli et al., 1987
Hanek et al, 1988
Kiss, 1976a; 1977a,b
Mahy, 1977
Reizer, 1975
Welcomme, 1979a

SEYCHELLES

1. GEOGRAPHY AND CLIMATE

Seychelles (with a surface area of 443 km²) consists of an archipelago of over 100 islands, 46 of which are permanently inhabited. The islands are the high point of the north-south running granitic Mascarene Ridge of the Indian Ocean. The landscape is rugged, with small fertile hollows between rock relief.

The coast has an almost constant warm temperature of 27°C and high humidity. Temperatures are lower at higher altitudes. The economy is based on agriculture (chiefly copra) and tourism.

2. HYDROGRAPHY

2.1 Lakes: None of significant size

2.2 Rivers, Floodplains and Swamps: Only short streams

2.3 Reservoirs: A small reservoir (cascade) near the airport on Mahè Island

2.4 Coastal Lagoons: None

3. FISHERY PRODUCTION/POTENTIAL

3.1 Aquaculture: There is no aquaculture (Vincke, 1989, pers.comm.)

3.2 Fish production and per caput supply: See Table 1

3.3 Inland catch range and potential yield: None

4. STATE OF THE FISHERY

4.1 Yield: There appears to be no inland fishery.

4.2 Factors influencing yield: Lack of sizeable inland water bodies.

4.3 Future development possibilities

Some development in aquaculture may be possible, but inland fishery production may never become very important.

5. KEY BIBLIOGRAPHY (None)

Table 1. FISH PRODUCTION AND PER CAPUT SUPPLY - Seychelles 1970–1987

¹ Source: FAO
² Source: FAO Fisheries Department FISHDAB
³ Marine exports were as follows: 1980: 677 t; 1981: 333 t; 1982: 619 t; 1983: 748 t

6. WATER BODIES DIRECTORY

CASCADE RESERVOIR

SWAZILAND

1. GEOGRAPHY AND CLIMATE

Swaziland has a surface area of 17 364 km². It consists of a highland plateau dipping to the south.

The climate varies from humid near-temperate in the highlands to almost tropical subhumid at lower elevations. Rainfall is concentrated into a few violent storms. The economy depends on commercial agriculture and mineral extraction.

2. HYDROGRAPHY (adapted from Chondoma, 1988) (See Fig. 1)

Swaziland is fairly rich in water resources, being traversed by five large rivers and with sufficient rainfall for rainfed agriculture in the highveld and middleveld. The water quality is generally good for fish farming.

Murdoch (1970), Tate and Lyle (1980), and USACE (1981) give the details of water quality parameters and their suitability to fish farming. Table 1 gives the summary of the water quality parameters (Chondoma, 1988).

Table 1. WATER QUALITY PARAMETERS

Sources: Murdoch (1970), Tate & Lyle (1980), and USACE (1981)

2.1 Lakes: None of significant size.

2.2 Rivers, Floodplains and Swamps

Swaziland is drained by five major rivers: the Mlumati, Nkomazi, Mbuluzi, Lusutfu and Ngwavuma. Of these, only two (the Mbuluzi and Ngwavuma) originate within Swaziland; the other three originate in South Africa (see Fig. 1). All these major rivers flow in an easterly direction, crossing the highveld, middleveld, lowveld and the Lubombo plateau, draining into the Indian Ocean.

Nearly all streams in the highveld are perennial, as opposed to the lowlands where most streams (except for the large rivers) flow only after large local storms. Even in those rivers which flow all year round, the discharge is markedly seasonal, depending on the rainfall in their catchment. A number of large dams (Table 2) have been built to store water and control the flow to irrigation schemes.

Table 2: MAJOR DAMS AND THEIR PRIMARY USE
(Chondoma, 1988)

* Based on SADCC (1984) estimate for a productivity of 20 kg/ha/yr. See also separate entries under section 6 and Table 4.

The total discharge as the rivers enter Swaziland is 60 m³/s or 3.6 million litres per minute; the total discharge is 144 m³/s or 8.6 million litres per minute when leaving Swaziland (Goudie & Williams, 1983; Murdoch, 1970). Figure 1 shows the major river basins and their mean discharge. However, water extraction, both in South Africa and Swaziland, increasingly decrease these values. Currently there is a tri-partite Joint Permanent Technical Committee (JPTC) between South Africa, Swaziland and Mozambique to regulate water releases from South Africa to Swaziland and from Swaziland to Mozambique.

Swaziland has no natural lakes, swamps or floodplain areas of economic importance.

2.3 Reservoirs

During the past 20–30 years a number of dams and reservoirs have been built for irrigation, community water supply, animal drinking and power generation. The dams and reservoirs range in size from a few large constructions, such as Mojoli Dam (8 400 ha), through many medium-sized reservoirs of 40–100 ha, to a large number of small reservoirs of 0.5–2 ha. Table 2 shows some of the major dams, their sizes and primary use. Most of these reservoirs and dams have been stocked with fish and some could support small-scale capture fishery or serve as foci for fish farming development.

2.4 Coastal Lagoons

None; Swaziland is landlocked.

3. FISHERY PRODUCTION/POTENTIAL

3.1 Aquaculture (adapted from Chondoma, 1988)

Swaziland's climate is favourable for fish farming, ranging from warm-water fish in the lowveld to cold-water fish in the upper reaches of the highveld.

There are no statistical records showing the national annual fish production from aquaculture. SADCC (1984) estimated that the total annual fish production in 1982 from aquaculture was about 50 tons, while the estimates of Vincke (1989, pers.comm.) are far lower (see Table 3).

There were about 500 family fish ponds in 1978. It was estimated that, in 1988, there were about 800 productive family ponds averaging between 100 and 200 m² in size, with an annual average production of 2 000 kg/ha. This estimate gives a productive total pond area of between 8 and 16 ha, producing between 16 and 32 tons. However, the exact location of most of these family fish ponds is not known for certain. In 1986 the Fisheries Section sampled and documented only 161 family fish ponds.

There are a few individuals and forest companies running small trout farms in the highveld; their production is also not known for certain.

Currently five fish species are successfully cultured: the rainbow trout (Salmo gairdneri), tilapia (Tilapia rendalli and Oreochromis mossambicus), sharptoothed catfish (Clarias gariepinus) and the common carp (Cyprinus carpio). C. carpio and S. gairdneri are introduced species.

A number of factors limit the rate of aquaculture development in Swaziland. Among these are: the lack of trained manpower; lack of aquaculture policy and a development plan; and inadequate infrastructure, particularly for fish seed production.

Swaziland has a potential for aquaculture development, especially in the lowveld in integration with irrigation schemes. Given the climatic conditions, the development of infrastructure, and the current nutritional and socio-economic situation, aquaculture has a high chance of success in Swaziland. However, Swaziland will need long-term financial and technical assistance if aquaculture is to succeed.

3.2 Fish production and per caput supply

(See Table 3 on following page.)

3.3 Inland catch range and potential yield

No catch or potential yield figures are available for the major rivers: Komati, Lusutfu, Mbulugi, Mlumati and Ngwavuma.

Potential yield figures for reservoirs are given in Table 4.

Table 3. FISH PRODUCTION AND PER CAPUT SUPPLY - Swaziland, 1970–1987

¹ Source: FAO
² Source: FAO Fisheries Department FISHDAB; see also text (section 4) and Table 4.
³ included in “Inland capture” if not specified
⁴ - = data not available
⁵ Vincke (1989, pers.comm.)

Table 4. POTENTIAL YIELD FOR RESERVOIRS

¹ Sources: see text

4. STATE OF THE FISHERY (adapted from Chondoma, 1988)

4.1 Yield

Swaziland does not have large natural lakes and, as a result, there is no capture fishery of any significance. Small-scale capture fishery has developed around the small man-made irrigation dams and reservoirs. The last estimated and reported catch from waters of Swaziland was 44 tons in 1987 (FAO, 1987). SADCC (1984) estimates the current catch to be 100 tons annually and 50 tons from aquaculture. This may be an overestimate of current catch as there has been a decrease in the number of fishing groups in recent years.

4.2 Factors influencing yield

Swaziland does not have natural lakes nor large man-made lakes to develop a major inland capture fishery. However, there are a number of small- to medium-sized dams and reservoirs which could develop small capture fisheries. The development of capture fishery in these small water bodies has been one of the main aims of the fishery development in Swaziland.

4.3 Future development possibilities

There is no reliable estimate of the potential production from the small water bodies and rivers in Swaziland. Clay (1972) estimated that production from the small water bodies could range between 20 and 150 kg/ha/yr, depending on the conditions of the dam; Clay also estimated that Sand River Dam (about 700 ha) alone could produce 80–150 t/yr. SADCC (1984) estimates the annual potential production from inland waters of Swaziland to be 200 tons, excluding aquaculture. These dams are primarily used for irrigation and are subject to considerable water level fluctuations. Even when these fluctuations are taken into consideration, SADCC's estimate of 200 t/yr works out to about 20 kg/ha/yr, if only the area of the major dams (Table 2) is used. Thus the real potential production may be higher than this estimate (see Table 4).

There is no estimated potential for aquaculture production. However, it is possible to double the current estimated annual production of 50 tons by improving the fish farming systems and utilizing new water bodies within the existing water use pattern. Therefore, increase in fish production will have to come also from aquaculture.

5. KEY BIBLIOGRAPHY

Chondoma, 1988

6. WATER BODIES DIRECTORY

Fig. 1. RIVER BASINS AND THEIR DISCHARGE
(Goudie & Williams, 1983)

KOMATI RIVER
(International water)

HAWANE RESERVOIR

LUPHOLO RESERVOIR

MJOLI RESERVOIR

MLILWANE RESERVOIR

NYANTENI RESERVOIR

PONGOLAPOORT RESERVOIR

SAND RIVER RESERVOIR

SIVUNGE RESERVOIR

TOBOTSA RESERVOIR

VAN AEKE RESERVOIR

7. BIBLIOGRAPHY

Chondoma, 1988
Clay, 1972
Goudie & Williams, 1983
Murdoch, 1970
SADCC, 1984
Tate & Lyle, 1980
USACE, 1981